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(No' Model.) 5 Sheets-Sheet 1.

R. H. THORPE, APPARATUS FOR REGULATING HYDRAULIC POWER. No. 528,419.Patented July 24, 1894.

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R.H.THOR'P E. I APPARATUS FOR REGU-LATING HYDRAULIG POWER.

No. 523,419,. Patented July-24, 1894.

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Y E l nwnzwr (N6 Model.) v 5 Sheets-Sheets. R. H. 'I'HORPE.- I VAPPARATUS FOR- REGULATING HYDRAULIC POWER. 7 No. 523,419. Patented July24, 1894.

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i R. H. THORPE. APPARATUS FOR REGULATING HYDRAULIC POWER. v No. 523,419.Patented July 24, 1894.-

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APPARATUS FOR REGULATING HYDRAULIC POWER. No. 523,419. v Patented July24, 1894.

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NITED- STATES PATET Fries.

ROBERT HENRY THORPE, OF LONDON, ENGLAND.

APPARATUS FOR REGULATING HYDRAULIC POWER.

SPECIFICATION forming part of Letters Patent No. 523,419, dated July 24,1894.- Application filed December 9. 1891- Serial No. 414,492. ;(Nomodel.) Patented in England December 9, 1891, No. 21,628.

$ at. whom it may concern.-

Be it known that 1, ROBERT HENRY THORPE,

engineer, asubject of Her Majesty the Queen v the purposeof regulatingthe power and to a certain extent the quantity of high or main pressureliquid employed for effecting the desired quantity of work, or in otherwords to vary the resultant power depending upon the work it is calledupon to perform, the high or main pressure being assumed as remainingconstant in either case.

The invention mainly consists of improvements upon the inventions setout in specifications of United States Patents No. 429,664 and No.446,799, and in order that the same may be clearly understood, referenceis made to the accompanying drawings, which form part of thisspecification, and in which Figures 1 to 5 illustrate the invention asapplied to a single motor cylinder.

In the drawings Fig. 1 represents the position of the parts when fullpower is applied, and Fig. 2 with decreased power and reducedconsumption of high or main pressure liquid.

7 In Figs. 3, 4 and 5 the position of one of the parts or connectionsshown in Figs. 1 and 2 is somewhat changed while still enabling the sameresult to be attained, Fig. 3 representing the parts in position toadmit full power, while Fig. 4 indicates their position for reducedpower with proportionate reduc-. tion of high or main liquidconsumption, while Fig. 5 represents the high or main pressure as beingentirely shut off the liquid circulating from end A to A, and toexhaust.

Considering first Figs. 1 and 2 it will be noted that end A of thecylinder is connected to main or supply pipe D by pipe S, the inflowbeing governed by stop valve F. and operating valve F, the latter alsogoverning the direct exhaust through pipe G from end A of cylinder. Abranch pipe I with regulating valve Q connects end A of cylinder throughpipes S and Iwith cylinder J behind piston K. A branch pipe H withregulating valve P connects cylinder J in front of pistonK with main orother source of supply D at a point outside of valve F, so that the fullmain pressure may be exerted thereon.

'It will be noted that the piston rod of the piston K has a considerablecross section and that the area of the piston K which is exposed topressure from the main is therefore less than the area of the oppositeside of the piston. The.piston K and the cylinder J with its connectionsform an automatic operating device for the valve L. This device differsfrom those shown in my prior patents in that it is notin any Wayalfectedby Weights or springs, but is operated entirely by thedifierence in effective pressure upon opposite sides of the piston K. Itdoes not depend upon the absolute pressure in the main, but,

upon the difference between the pressures in the main and the workingcylinder, whether they are high orlow. With prior devices of this naturethe valve would not be operated automatically if the pressure in themain were lower than the normal pressure for the reason that in additionto the differential piston or pistons used, a weight or spring was addedto assist in controlling the valve thus creating a constant resistance.In my present invention the piston K is usually moved automatically onaccount of the difierence between the main and the initial pressure.Should the main and the initial pressure in any instance be exactlyequal however, the valve will still be moved onaccount of thedifferential piston'K. In either case therefore there will be aneifective difference between the main and theinitial pressure which willoperate thevalve.

When the valves are in position shown in Fig. 1 full pressure enteringthrough D is exerted behind piston B, the otherend of the cylinder beingopen to tank X by exhaust G behind B to-G when the pressure behind Kbeing relieved, the direct pressure from main in front of K overcomesfriction of valve L which is moved in the direction of least resistanceover to the position shown in Fig. 2, in which position it will remainuntil piston B is called upon to perform work which requires the largerpower. On return stroke of piston B the water in end A is caused to flowback through pipe S and operating valve F to exhaust pipe G, enoughpassing through check valve R (which will allow water to pass from G toM but not to return) to fill end Athe remainder which is equal to thequantity displaced by piston rod 0 going to tank X.

With the parts as shown in Fig. 2 the apparatus is adapted to Work atdecreased power with a decreased consumption of high or main pressurewater, as the ends A and A of cylinder are both open to pressure, thepower exerted being proportionate to the sectional area of piston rod C.So long as the work to be done by U can be effected at the reduced powerso long will the pressure in front of K be sufficient to hold valve Linposition shown in Fig. 2 against pressure behind K, which as is wellknown will vary in proportion to resistance of piston B, or of the workto be done. The area of piston K can be proportioned so that fullefiective power shall only be put on piston B when the resistance orwork to be done calls for a pressure above a certain number of poundsper square inch.

For the purpose of illustration let it be assumed it will take apressure of five hundred pounds per square inch behind- K to equal thepressure from main plus the friction, then so long as the work requiredto be done by piston B does not require a greater number of pounds persquare inch, so long will valve L remain in position shown in Fig. 2,and as the work is being done the water displaced by travel of B- willbe passed through M, L, N, F and S to other side, thereby only using thewater required for the first or reduced power of the motor.

For the purpose of further illustration let it be assumed that the workto be done requires a greater number of pounds per square inch than willbe suificient to overcome the pressure from main on K plus friction,then the initial pressure per square inch will rise according to theresistance of piston B and be transmitted through pipes S and I tocyliuder J, and will cause K to travel in direction of least resistanceor over to the position shown in Fig. 1, thus opening the end A ofcylinder to exhaust G through pipes M and O, and causing the apparatusto work on the larger power, as soon as the work has been done and themotor stopped initial pressure behind K is relieved and the valve L isautomatically moved back into its normal position'as shown in Fig. 2.When moving from the small to larger power as soon as valve L has movedforward sufficiently to throttle the outlet N without sufficientlyopening exhaust port 0 the resistance to B in cylinder will beincreased, and it will be impossible for this reason for the valve toreturn while piston B is moving forward performing work, thus the largerpower being provided will not change until motor comes to rest when itwill be free to return to the smaller power.

If valve L be constructed so that port N is entirely out off from pipe Mbefore the latter is put into communication with 0, then the resultwould be as stated, but it may be so constructed that there is a slightpassage between 0 and M, and M and N when the valve is midway, saidpassage being insufficient to allow water from the main to go to waste,but yet sufficient to allow the Water from to take the direction 0 or Nwithout materially checking the motion of piston B in the cylinder.

The special value of valve R is to allow water from the exhaust ordischarge to pass into end Aof the cylinder whenever piston B shall beon the return stroke, thus avoiding the possibility of there ever beinga vacuum 1n end A of said cylinder whatever the position of valve L.When piston Bis returning there will always be suflicient water comingthrough pipe Sto fill'end A of cylinder, but notwithstanding I generallyprefer to use a discharge tank placed in such a position that the watershall run from it by gravity through check valve B into said end.

When it is desired to obviate any possibility of valve L closing pipe Nand failing to open the discharge from-M through 0 to G,a connection maybe made directly from plpe M to pipe S, such connection V being pro-Vided with a check valve T which will permit a flow from M but not fromS. Such a connection is illustrated in Figs. 3, and 4:, and.

renders the use of pipe N unnecessary.

Ifit be assumed that valve Fhas been moved allowing pressure from themain to be exertedbehind piston B through pipe S, and that theresistance of piston B has caused initial pressure behind K in cylinderJ to be raised sufliciently to overcome the pressure from the main infront of K plus the friction, then valve L would be moved over toposition represented in Fig. 3, thus opening the end A of the cylinderto exhaust G through M and O, and the motor would then be working on thelarger power. After the motor has been stopped the initial pressurebehind K being relieved valve L is automatically moved back as alreadydescribed, to the position shown in Figs. 4 and 5, cutting offcommunication from front of piston B to exhaust G.

If it be assumed that the pressure from the main is being exerted behindpiston B but the resistance given is not enough to raise initialpressure behind K sufiiciently to overcome the resistance in front, thenthe water which is in front of piston B would be put under pressure andowing to the difference in area of piston 13 on opposite sides thepiston will travel forward, the water displaced by such travel beingcompelled to pass to end A of by means of valves W placed in piston B,or.

by so constructing the piston and packing that the water can pass fromthe end A to end A of the cylinder as shown in Fig. 5.

In the practical operation of an apparatus,

" such as I have described, it is necessary that the change in theposition of the valve L, and the piston K which governs its movements,from that position which causes the reduced power to be exerted upon thepiston B, to the position which permits the full power to be exertedthereon,as in the starting with a heavy load,-should take place veryrapidly in order that there should not be a moments delay; and thereforethe water must pass through the pipes I and H, and through theregulating valves therein, with great rapidity -and the utmost freedom.On the other hand when the valve L is moved in the opposite direction,as it will whenever the lesser or reduced power may operate theapparatus, it is important and necessary that the return should be madevery slowly in order that the water from the supplemental cylinder Jshould not be forced too suddenly into the main cylinder, as this wouldcause the car to jump. To this end, the valvesP and Q, which I term theregulating valves, are so constructed that they permit thewater to flowfreely and rapidly when moving in the direction to cause the piston K tomove from the position shown in Fig. 2 to that shown in Fig. 1, butwhich operate to cause a retarding of the movement of the water when thepiston is moving in the opposite direction. In using the term regulatingvalve, therefore, in this specification, I mean a valve having thecharacteristics of operation just referred to.

What I claim is 1. The combination, with a motor cylinder,

the piston therein, the channels, and a valve,

governing the inlet and exhaust channelfrom the working end of the saidcylinder, of a valve governing the discharge from the piston rod workingend of the said cylinder,

end of the cylinder, means for operating the latter valve automaticallyby the effect ve difference between the main pressure and initialpressure, even if these vary from time to time, and a supplementarypassage provided with an automatic valve connecting the opposite ends ofthe motor cylinder, substantially as set forth.

2. The combination with a motor cylinder, the piston therein, thechannels, and a valve governing the inlet and exhaust from the m of avalve which governs the discharge from the piston rod end of the saidcylinder, means-for operating the said valve automatically by theeffective difference between the main pressure and initial pressure, anda supplemental passage provided with a check valve connecting thedischarge pipe from the piston rod end of the motor cylinder with theexhaust pipe, substantially as set forth.

3. The combination with a power cylinder piston channels, a valvegoverning the inlet and exhaust of the working end and apiston valveautomatically operated by the efiective difference between main andinitial pressures governing the exhaust of the piston rod end, ofregulating valves interposed between the supply pipe and the piston rodend of the piston valve cylinder and between the working end of saidcylinder and the working end of the power cylinder, substantially as setforth. 4. The combination with a power cylinder and piston, of a valvegoverning the exhaust from the piston rodend of the cylinder andautomatically operated by the effective difference between main andinitial pressures, a supplementary passage provided with an automaticvalve connecting thepiston rod end of the motor cylinder with theexhaust passage way and an automatic supplemental valve interposedbetween the piston rod end and the Working end of said cylinder,substantially as set forth.

' In testimony whereof I have hereunto set my hand in the presence oftwo subscribing witnesses.

ROBERT HENRY THORPE. Witnesses:

PHILIP M. J USTICE, ALLEN PARRY J onus.

